With the increasingly more stringent requirements for reducing the levels of sulfur and nitrogen contained in petroleum derived hydrocarbon product streams there has been an ongoing effort to find new or improved hydroprocessing catalyst formulations and products that may suitably be used to more economically provide for the required sulfur and nitrogen reductions in the hydroprocessing of such petroleum derived hydrocarbon streams.
Typical hydroprocessing catalysts known in the art can include a Group VI metal (Mo and/or W) and a Group VIII (Co and/or Ni) as active components which are supported on an inorganic oxide support material. These catalyst components may be combined and treated in a many different ways to give catalyst compositions having certain desired properties.
One example of a hydrotreating catalyst proposed for use in the hydrodesulfurization, hydrodenitrogenation, and hydrodemetallization of various petroleum fractions is disclosed in U.S. Pat. No. 7,235,173. This patent discloses a hydrotreating catalyst containing a group VIB and/or a group VIII with an organic compound as an additive. The organic additive is a compound that contains at least one nitrogen atom and corresponds to a specifically defined generic formula. The catalyst of the '173 patent is prepared by incorporating the hydrogenation metals into a matrix material, such as by ion exchange or dry impregnation of the substrate followed by a calcination. The organic compound may be introduced into the catalyst composition by dry impregnation or by co-impregnation simultaneously with the metals or it may be present in the sulfurization feedstock. The '173 patent indicates that its catalysts that employ the particular organic additive exhibit improved activity over the comparative catalysts that do not employ an additive.
In U.S. Publication US 2009/0298677 is disclosed a hydroprocessing catalyst that includes a carrier containing catalytically active metals from Group VIB and Group VIII of the periodic table and a chelating compound. The chelating agents that are suitable for use in the hydroprocessing catalyst are preferably hydroxycarboxylic acid, especially those that contain one or more carboxyl groups and one or more hydroxyl groups. One preferred chelating agent is citric acid. The hydroprocessing catalyst is prepared by contacting a carrier with an impregnation solution of catalytically active metals and a chelating agent followed by heating the impregnated carrier to provide a catalyst having a loss on ignition that is within a desired range. The heating temperature is to be less than a temperature that would result in significant or substantial degradation of the organic chelating agent.
As is indicated in these patents, there is an ongoing need to find new and improved hydroprocessing catalyst compositions that have improved catalytic properties. There is a need to find hydrotreating catalyst compositions that are highly active and stable when used in the treatment of petroleum derived hydrocarbon process streams that have high concentrations of sulfur and nitrogen.